1984 force 125 , runs only about 10mph? Help

[aplus]

I have a 1984 force 125 on a 19 ft bayliner capri. It will only run about 10-15 mph. I changed out the fuel pump diaphram and replaced the bowl gaskets on the carberater. One thing i noticed is when we are crusing along i can put my hand over the intake of the lower carberater and it will pick up speed. If i do the same to the top carberater it will stall. Any suggestions.<br /><br />Thanks <br />Aplus

 

[imported_bjs]

Re: 1984 force 125 , runs only about 10mph? Help

check compression first.could be a reed valve.maybe an ing.problem i dont know what kind of ing.you have.check spark.

 

[aplus]

Re: 1984 force 125 , runs only about 10mph? Help

I am no mechanic this is the first boat Ive had to work on, but it seems to me its in the carburetor, or the reeds. I dont understand how it could be a compression problem.<br /><br />Thanks for youre reply

 

[eurolarva]

Re: 1984 force 125 , runs only about 10mph? Help

Your motor can run with a cylinder or two not working. This becomes more obvious at higher speeds. Compression test will rule out a blown head gasket or cylinder damage. If compression numbers are good the next step is to find out if this is electrical or fuel related. Compression testers are about 30 bucks and easy to use. If you dont do the compression test take the plugs out and check the tips of each plug. If one is clean and the others are dirty chances are the clean plug is the bad cylinder.